Intelligent watt-hour meter is a kind of energy meter which uses computer technology and communication technology to form a electric meter with intelligent chip (such as CPU) as the core, and has the functions of electric power metering and timing, charging, communication with upper computer, and power management.

Principles and characteristics of smart meters

1. the composition and principle of smart meters
Smart energy meter is mainly composed of electronic components. Its working principle is first through the real-time sampling of the user's supply voltage and current, and then the use of a dedicated watt-hour meter integrated circuit, the sampling voltage and current signals are processed, and converted into a pulse output proportional to the electrical energy, and finally through the single-chip microcomputer. The pulse is displayed as electricity consumption and output.
Usually we call the number of pulses emitted by the A/D converter when measuring a kilowatt-hour by smart meter as pulse constant. For smart meter, this is an important constant because the number of pulses emitted by the A/D converter in a unit time will directly determine the accuracy of the meter.

2. characteristics of smart meters
Because of the design of electronic integrated circuit and the function of remote communication, it can be connected with computer and controlled by software. Therefore, compared with inductive meter, intelligent meter has great advantages in both performance and operation function.

(1) Power Consumption: Because the smart energy meter is designed with electronic components, the power consumption of each meter is only 0.6-0.7 W. For multi-user centralized smart meter, the average power to each household is smaller. In general, the power consumption of each induction meter is about 1.7W.
(2) Accuracy: The error of 2.0 level electric meter in the range of 5%-400% calibration current is (+) 2%, the error is smaller. The error range of induction watt-hour meter is + 0.86% ~ - 5.7%, and because of the mechanical wear and tear this insurmountable defect, leading to the induction watt-hour meter more slowly, the final error is more and more big. State Grid has conducted spot checks on inductive meters, and found that more than 50% of the inductive meters after five years of use, the error is beyond the allowable range.
(3) Overload and power frequency range: the overload multiple of smart meters can generally reach 6-8 times, with a wider range. The working frequency is also wide, ranging from 40 to 1000Hz. The overload multiplier of induction meters is generally only 4 times, and the working frequency range is only 45 to 55Hz.
(4) Functions: Because of the use of electric meter technology, smart meters can be connected to the computer through the relevant communication protocols, and the hardware control and management can be realized by programming software. Therefore, the smart meter not only has the characteristics of small size, but also has the functions of remote control (remote meter reading, remote power outage), multiple rate, identification of malignant load, anti-theft, prepaid electricity and other functions, and can meet the different requirements of control functions by modifying the different parameters in the control software, and these functions. It can be difficult or impossible for traditional induction meters.